Research On Single-phase Inverter Optimization Based On Predictive Control

As the core device of energy conversion,the inverter has become more and more widely used in daily life.The traditional single-phase inverter system usually adopts PI control,and the PI control switching frequency is fixed under the condition of SPWM modulation.With the increase of switching frequency,the switching loss will increase drastically.Therefore,this paper presents an optimization method for single-phase inverter based on variable coefficient predictive control.Through designing the coefficient of objective function,the unity of current tracking and switching loss control were realized.Efficiency was improved since the given current was perfectly tracked while high current switching action was suppressed,and the energy conversion efficiency of the system is improved.Firstly,the current status of the nowadays energy sources were described.Then the advantages and development of alternative source was illustrated.Also the development and application of inverters were discussed.The control methods of inverter were analyzed and compared.Then the necessary of predictive control in inverters was shown.Secondly,three types of topology and the characteristics of control methods for single-phase inverters were introduced.There are so much kinds of filters to chose in the single-phase invert system,such as LC and LCL,their transfer functions and characteristics were calculated and introduced.Thirdly,combining the above,the topology structure and controller for this paper can be adopted.According to the working principle of predictive control,the single-phase grid-connected inverter topology was modeled and the expression for predictive equation for output current was obtained.The objective functions was obtained based on control requirements,which includes current tracking and reduction of switching frequency,By solving the optimization problem,the controller outputs was applied to the system at each step,the purpose of real-time rolling correction was achieved.Through the comparison of the results and the number of switches by MATLAB simulation the effectiveness of the controller designed was verified.Fourth,the hardware circuit was designed depending on the simulation,including the sampling circuit,the absorption circuit and the drive circuit,and the parameters were calculated.In addition,the parameters of main devices such as IGBT and filterinductor were calculated and selected according to the designed system parameters,ensureing the system operating safely and stably.Lastly,a 3KW inverter was built up,the driving waveform and dead time were illustrated,then two experimentals about current tracking and switching frequency reduction for large current were verified.